Korg Lambda ES50

The Korg Lambda is a fully polyphonic 48-key preset synthesizer released
in 1979. It features two types of sound - Percussive (Electric Piano,
Clavi, Piano, Harmonics) and Ensemble (Brass, Organ, Choir, Strings I,
Strings II). The Percussive sounds have a simple fast attack and
variable decay envelope, and the Ensemble sounds have both preset and
variable attack/release envelopes. Each key is articulated
independently, so there is no note-stealing as experienced on synths
limited to a handful of voices. The downside of this is the relative
lack of programmability, but the presets sound good, particularly when
layered (they are all available simultaneously).

The Lambda uses divide-down technology from three Top Octave oscillators
to provide the basis for its sounds. The three oscillators are mixed and
filtered using fixed circuits to create the preset sounds, but there are
also controls on the front panel for basic low-pass filtering of the
Percussive and Ensemble tones, and each section has its own volume
control. There is also a control for "click" (used to add
attack to the EP sound) and a filter cut-off control for the Brass
sound, which has its own paraphonic filter - tuned to give a slightly
resonant peak to the sound, and with its own preset filter envelope.
This re-triggers on every keypress, so held notes will also be reshaped
when new ones are played. In practice this is not much of a problem.

An Octave switch puts the keyboard in regular or Octave Down mode. The
three oscillators can be detuned to thicken the sound further, and there
is a separate analog "chorus phase" (really just a chorus) for
each of the Percussive and Ensemble sections. These can be switched
on/off independently but share the same sweep control, which is via the
joystick on the modulation panel to the left of the keyboard. The
joystick also acts as a pitch bend control. Vibrato can be switched off
the Ensemble sounds. Percussive sounds feature a variable Tremolo and a
Sustain switch that turns Decay into a Release.

Round the back, there are plenty of interface jacks for a synth of this
type. Aside from the headphone out, the mono mix out, and the stereo
outputs, there is a short-to-ground Keyboard Trigger output, a Sustain
pedal input, and an Expression input jack, switchable between
Percussive, Ensemble, or both.

The Lambda is a solidly-built instrument, and its large top panel is
perfect for laying out some effect pedals and/or a mono-synth. Despite
its preset nature, the Lambda is a more versatile synth than it might at
first appear, partly due to the quality of its sound, but also the
simple yet useful modulation and tone-shaping controls. It really shines
through a phaser and some reverb, and is eminently playable.

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